Novel Research Approach Combined with Dielectric Spectrum Testing for Dual-Doped Li₇P₃S₁₁ Glass-Ceramic Electrolytes

Abstract

Owing to the expanding function of Li-ion transmission channels, it is important to explore the doping effects of different compounds into sulfide solid electrolytes to improve their electrochemical performances. However, it is hard to characterize the doping behaviors within sulfide solid electrolytes with low crystallinity and poor stability just by conventional crystallography analytical methods. In this work, the dielectric spectrum testing combined with other analytical methods, such as 7Li solid-state nuclear magnetic resonance, X-ray photoelectron spectroscopy, and the electrochemical method, have been applied to investigate the dual-doping behaviors of WS2 and LiBr within Li7P3S11 glass-ceramic electrolytes. This research method can not only evaluate the internal acting effect between the skeleton of sulfide solid electrolytes and the migrating kinetics of Li ions but also explore the capacitance at the interfaces of LiCoO2/sulfide solid electrolytes. The experimental results show that the number of Li ions with fast transport velocity within Li2S-P2S5-based solid electrolytes has been increased. Meanwhile, the interfacial capacitances between Li2S-P2S5-based solid electrolytes and the LiCoO2 cathode have decreased after dual-doping of WS2 and LiBr, indicating a synergetic effect for the doped Li7P3S11 glass-ceramic electrolytes in terms of the ionic conductivities and interfacial compatibilities. This work may provide a novel analytical approach to explore both the diffusion kinetics and interfacial behaviors for the solid electrolytes of lithium batteries.

Tailored Li7P3S11 Electrolyte by In2S3 Doping Suppresses Electrochemical Decomposition for High-Performance All-Solid-State Lithium–Sulfur Batteries

“…Both the binding energies show the band moving toward the higher energy from 444.3 eV for In 2 S 3 , suggesting that In 2 S 3 was successfully doped into the original structure of the electrolyte. In contrast, binding energies of S 2p and P 2p spectra of pristine Li 7 P 3 S 11 (Figure S2ab) reflect the basic structural/conductive units without tuning, which agrees with the prior literature. ,,− Moreover, the Raman spectroscopic testing was performed further to investigate the structural changes of glass ceramics. Figure d shows the deconvoluted Raman spectra from 300 to 500 cm –1 .…”

“…As displayed in Figure S1a, the 31 P NMR spectra of Li 7 P 3 S 11 - x In 2 S 3 ( x = 0, 0.005, 0.01, and 0.02) exhibit two main peaks at 90.6 and 86.3 ppm, associated with the P 2 S 7 4– and PS 4 3– structural units in the electrolyte, respectively. , Beyond that, there is a weak peak at about 104 ppm, consistent with structural units P 2 S 6 4– . The evolution of P 2 S 7 4– to P 2 S 6 4– can be induced at elevated temperatures or with longer annealing. , The NMR pattern shows that no obvious change happens in the framework of LPS before and after doping, suggesting that In 2 S 3 doped into the LPS matrix did not destroy the original structure. Nevertheless, the relative intensity of each peak is different with the increase in the amount of In 2 S 3 .…”

“…28 The evolution of P 2 S 7 4− to P 2 S 6 4− can be induced at elevated temperatures or with longer annealing. 29,30 The NMR pattern shows that no obvious change happens in the framework of LPS before and after doping, suggesting that In 2 S 3 doped into the LPS matrix did not destroy the original structure. Nevertheless, the relative intensity of each peak is different with the increase in the amount of In 2 S 3 .…”

Atomic-scale study clarifying the role of space-charge layers in a Li-ion-conducting solid electrolyte

“…The Li 0.33 La 0.56 TiO 3 material can host up to 3. 44 Li per perovskite unit cell with its A-sites and 3c interstitials. Compared with this value, the Li contents in the SCLs (0.33−0.66 per perovskite unit cell) are in fact rather small, and the variation is also very limited.…”

Emerging Role of Non-crystalline Electrolytes in Solid-State Battery Research

“…While the operating potential was limited due to the use of a Ti 2 S cathode, the cell did show enhanced cyclability over a pure LPS electrolyte. Zhang and coworkers took a similar route by doping an LPS electrolyte with LiBr 2 and WS 2 to promote a reduction in internal polarization and enhanced conductivity in an ASSB with an LiCoO 2 cathode and Li-In alloy anode (Zhang et al, 2019). The resultant composite electrolyte demonstrated excellent cyclability which the authors attributed to a reduction in space charge polarization at the electrode/electrolyte interfaces.…”